The present invention relates to laser diodes, and in particular to the construction and operation of emitter arrays.
Although diode lasers are presently available in linear arrays, or xe2x80x9cbars,xe2x80x9d the individual emitters are not separately addressable; that is, the lasers must all be on or off. This is due to the thermal and electronic interaction that inevitably results from containment within a single solid structure. xe2x80x9cCrosstalkxe2x80x9d causes operation of one device to affect nearby devices, thereby producing mutual interference. Accordingly, the current state of the art precludes individual operation of the lasers in a single diode bar; simultaneous device operation ordinarily entails electrically and physically separate devices.
A need therefore exists for multiple-device packages that have closely spaced diodes, but which also permit independent operation of the individual lasers.
The present invention achieves sufficient thermal and electronic isolation among the emitters in a diode bar to permit separate addressability. In accordance with the invention, a laser emitter bar comprises first and second opposed, parallel surfaces each perpendicular to a third surface through which a plurality of emitters direct output. A first surface of the emitter bar is affixed to a xe2x80x9cstandoffxe2x80x9d element that has conductive surfaces connecting each emitter to a power source; these connections are maintained after a series of spaces is formed between the emitters of the emitter bar. The spaces are sufficient (generally 200 xcexcm to 1000 xcexcm) to ensure the absence of crosstalk among the emitters. The second surface of the emitter bar is then affixed to a heat sink to form a finished assembly.
In light of their separate addressability, two emitters in a single package may have different output power levels to facilitate, for example, production of image spots having different sizes.